A lens drive device for driving a lens for a camera mounted on a cellular phone or the like has been known which includes a movable lens body holding a plurality of lenses and moving in an optical axis direction, and a fixed body which movably holds the movable lens body through two flat springs (see, for example, Japanese Patent Laid-Open No. 2008-58659). In this lens drive device, a drive coil is wound around an outer peripheral face of a cylindrical sleeve which structures the movable lens body. Further, in this lens drive device, four magnets are disposed so as to face an outer peripheral face of the drive coil.
Further, in this lens drive device, the flat spring is structured of a portion fixed to the fixed body, a portion fixed to the movable lens body, and three arm parts which connect the portion fixed to the fixed body with the portion fixed to the movable lens body. Width and thickness of the arm part of the flat spring used in the lens drive device are commonly constant.
In recent years, in a market of a camera used in a cellular phone or the like, demand for downsizing, i.e., smaller or thinner of a camera has been remarkably increased. Therefore, demand for downsizing of a lens drive device which is mounted on a camera has been also remarkably increased. On the other hand, in recent years, in a market of a camera used in a cellular phone or the like, demand for high pixel density and high resolution has become higher and thus a diameter of a lens mounted on the lens drive device is liable to be larger. Therefore, it is difficult to make the lens drive device smaller or thinner. Further, in order to make the lens drive device smaller and thinner, the flat spring structuring the lens drive device is also required to be smaller and thinner. However, when the flat spring is made smaller and thinner, strength of the flat spring is decreased. Therefore, when an impact due to dropping of the lens drive device or the like is applied to the lens drive device, damage or excessive deformation of the flat spring may occur.